Thermoelectric conversion elements have been proposed where a plurality of N-type thermoelectric conversion parts and a plurality of P-type thermoelectric conversion parts are arranged alternately (see, for example, Japanese Patent Application Laid-Open No. 11-121815). This thermoelectric conversion element has a structure where each thermoelectric conversion part is partially exposed at the outer surface of the thermoelectric conversion element. In addition, examples of this type of thermoelectric conversion element include, for example, an element where an N-type thermoelectric conversion part is formed from an N-type oxide semiconductor material including an oxide, whereas a P-type thermoelectric conversion part is formed from a P-type semiconductor material including a metal.
However, when the previously described thermoelectric conversion element is used in an atmosphere in which a corrosive gas such as hydrogen sulfide is dispersed, a portion of the P-type thermoelectric conversion part exposed at the outer surface of the thermoelectric conversion element will be exposed to the corrosive gas. As a result, the metal included in the P-type thermoelectric conversion part will react with the corrosive gas, thereby forming impurities including the corrosive gas component in the portion of the P-type thermoelectric conversion part exposed at the outer surface of the thermoelectric conversion element. Because of this, the movement of carriers in the P-type thermoelectric conversion part is inhibited, thereby decreasing the output voltage of the thermoelectric conversion element.
The present invention has been made in view of the foregoing, and an object of the invention is to provide a thermoelectric conversion element capable of suppressing degradation of electrical characteristics in the thermoelectric conversion element even if a P-type thermoelectric conversion part is made of a material containing a metal, and a method for manufacturing the thermoelectric conversion element.